Question

Find two numbers whose LCM is 90

Answer 1

One way working this out is to find all the numbers that go into 90 by listing all the pairs of numbers that multiply to give 90

1 × 90
2 × 45
3 × 30
6 × 15
9 × 10

From here we can do trial and error:

Let's choose any two factors, say 2 and 3
By listing their multiples, we will find their LCM is 6, not 90

Then choose any two factors, say 3 and 6
By listing their multiples, we will find their LCM is 6, not 90

We can try some bigger number, say 45 and 90
by listing their multiples, we will find their LCM 90

Answer: 45 and 90

Answer 2

To find the LCM for 90 since it has a zero, the first LCM is going to be 10. And 10 multiplied by 9 is 90. You can also divide the 90 by 5 and get 18.